I really like my Bose cubes that are attached to the ceiling. Ceiling mounts would be preferred.
Have you listened to stereo music on two of the soundcubes?
I just want to make sure they have the dynamics to play as loud as you would ever want to listen to them.
Generally speaking a very small speaker like the Bose soundcubes is not really going to fill a living room/dining room space very well!
If a pair of soundcubes does the job, and with the task of being similar to the Bose system, but better build and sound quality, I would go with this package:
rslspeakers.com
With these to ceiling mount them:
rslspeakers.com
The one caution I would have is unlike your Bose these are pointed in one direction. I assume your combined two room are rectangular with a length much greater than the width. If you would be mounting them to shoot longways into the living room/dining room it should work fairly well.
If they will be mounted on the long wall to face across the short width of the room, I would go with these wall mount speakers (I believe this is an example of what ShadyJ is recommending above):
Infinity REFERENCE RS152 2-way surround channel speakers deliver smooth & crisp surround sounds and are strong and durable, yet incredibly lightweight.
www.infinityspeakers.com
You would not, however, mount these so close to the ceiling.
I would still use the same subwoofer with it on the assumption that since you are wanting to maintain the compact nature of the Bose, you probably want a fairly compact subwoofer (this is essentially a 15" cube).
rslspeakers.com
As a FYI, we generally consider a system like your Bose as a "lifestyle" speaker where you are compromising performance in the interest of minimizing the visual impact on the room. Consequently we feel a bit like our "hands are tied". The recommendations above are as close as I am comfortable getting to what you had with the Bose.